Kick with Lost Circulation Simulator, a Tool for Design of Complex Well Control Situations

Abstract

Abstract Being able to simulate drilling problems when operating within narrow margins between formation pressure gradients and fracture pressure gradients can cause great savings through improved planning. This is especially the case for HPHT and Deep Water wells. Lost circulation (i.e. underground flow) has in many cases proved to be a significant contributor to complex well control problems and drilling delays. The advanced kick simulator, RF-Kick, has recently been expanded to include the simulation of massive lost circulation. This tool allows the user to interactively investigate the problems of killing an influx while losses to formation occur. Kill procedures can thus be optimized through simulations. The fracturing is computed in a simple way. Only three numbers define the fracturing: the Fracture Initiation Pressure, the Fracture Propagation Pressure and the Fracture Closing Pressure. These pressures are supplied by the person using the simulator. The flow into (and out of) the fracture is determined by the flow needed to keep the fracture pressure at the fracture position. A user given fraction of fluid lost to the formation determines the amount of fluid re-entering the well. This paper presents a description of the model, and a simulation of a representative's deep water well. The simulation starts with a well taking a kick. The well is shut in. As the pressure builds up the formation breaks down and an underground blowout develops. The influx is stopped while limiting the loss to the formation using sufficient flow rate and kill mud. The example describes actions done to lower the pressure at the fracture to stop the loss of fluid, and the careful well operations needed to handle a well with a closing fracture. The simulation finishes when the fracture is closed and all the reservoir fluid has exited the well. Such simulations show the operator what equipment is needed for a successful kill, pump capacity (volume and power), and kill mud (density and volume). Simulating kick with lost circulation scenarios is novel and a significant contribution. This will enable the industry to perform planning and engineering of complicated well control situations. P. 25